Find the first term and the common different of an arithmetic progression if the sixth term is
25 and the sum of the six terms in the progression is 80.
a + 5d = 25 or a = 25-5d
sum(6) = 3(2a + 5d) = 80
6a + 15d = 80
6(25-5d) + 15d = 80
150 - 30d + 15d = 80
-15d = -70
d = 70/15 = 14/3
then a = 25 - 5(14/3) = 5/3
your turn to finish it